Really?! you were using the HD700 on your iPHone UNamped?! I've never heard the HD700's, but based on their impedance, I would've thought this would be impossible! Having that capability in a pinch is a nice option for me, so let me know!
They actually sound pretty nice from the iPod Touch (5th gen) unamped. You ARE going to miss that really wide soundstage that you get when amped, and the volume is not super high (albeit plenty loud in a non noisy environment). Plus, unless all your music is in AAC lossless, you are still contending with compressed music files (which, with the HD700 you can hear poor quality music easily) because of the limited number of formats supported.
With an amp (in my case a FiiO E17, but not my E17K) I think the combination actually sounds very good (still not the best it CAN be, but fantastic for portable). I think it sounds better than (my portable rigs) the FiiO X5 gen 1, and the X3II, both amped AND unamped (though the X3II is close behind), because of the iPod Touch's warmer presentation. It just doesn't have that SS sound to it like the iPod Classic 6th gen has (no longer owned by me).
Hardware wise, the iPod Touch 5th gen is really nice, it just suffers from the "Apple" stubbornness; few formats supported, no memory upgrade, etc... Oh what it could have been...
So, sitting in a hotel room, I prefer the iPod Touch + FiiO E17 (or even unamped), but if on the go, I like the X3II (unamped). Yes, I do wear them when on the go, but nothing like jogging, or working out, or etc... IMHO I don't really like the X5 gen 1 for the HD700 either amped OR unamped (though I absolutely love it for other phones).
Your best bet, if you don't have any AAC lossless, is to listen to Google Play Music, because they are streamed at 320k (which is not GREAT, but better than iTunes IMO). Honestly, if listening to the right kind of music, they DO sound pretty good. Example: the song "Sense" by Tenpenny Joke sounds fantastic on the iPod touch with the HD700.